docs: add package-level GoDoc for undocumented pkg/gofr subdirectories

[singhvishalkr]

Pull Request Template

Description:

• Adds doc.go files with package-level GoDoc comments for the 8 subdirectories under pkg/gofr/ that were missing documentation: cmd, config, migration, rbac, static, testutil, version, and websocket.
• Closes Enhance GoDoc for the directories section #995.
• These directories previously appeared with no synopsis on pkg.go.dev and in go doc output. With these additions, all 16 subdirectories now have meaningful descriptions.

Breaking Changes (if applicable):

• None. This is a documentation-only change with no code modifications.

Additional Information:

• Comments follow existing project conventions (// Package <name> ... style) and reference exported types using Go doc link syntax (e.g., [Request], [Migrate]).
• The 8 directories that already had package-level comments in source files (container, datasource, file, grpc, http, logging, metrics, service) are untouched.

Checklist:

• I have formatted my code using goimport and golangci-lint.
• All new code is covered by unit tests.
• This PR does not decrease the overall code coverage.
• I have reviewed the code comments and documentation for clarity.

Thank you for your contribution!

[singhvishalkr]

Hi team — just wanted to flag that this is a docs-only PR (8 new doc.go files, zero code changes), so it should be a quick review. All comments follow the existing // Package <name> ... convention and reference exported types via Go doc link syntax. Happy to adjust wording if needed!